Briefly stated, this invention relates to an improvement in expansion bands of a known type employing two rows of overlapping links, clip members connecting alternate links between rows, and spring members contained within the links together so that the links can be stretched apart and returned by the springs. Expansion bands of this type are well known in the art and described for example, in U.S. Pat. No. 2,689,450 issued to K. E. Stiegele on Sept. 21, 1954, U.S. Pat. No. 3,307,348 - Vanover issued Mar. 7, 1967, and U.S. Pat. No. 3,994,126 issued to K. A. Rieth of Nov. 30, 1976. Although this type of expansion band is very useful and economical to produce, nevertheless it becomes desirable to have an easy means for breaking into the expansion band at some point along its length, either for the purpose of making adjustments in overall length or for connecting or disconnecting sub-assemblies for manufacturing convenience. One construction for disconnecting sections of the band at any desired spot is shown in British Pat. No. 801,850, Complete Specification published Sept. 24, 1955 in the name of Rodi and Wienenberger A.G., which employs special spring members extending into opposite link rows and employs links of special shape. Another construction in a non-expansion type link bracelet utilizes a slideable member contained within the link which may be manipulated by a tool to disconnect the links, shown in German Offenlegungschrift No. 1,086,074 in the name of Albert Heinz.
Another construction for providing adjustment to an expansion band of the foregoing type is seen in U.S. Pat. No. 3,416,305 issued Dec. 17, 1968 to K. A. Rieth. This patent employs a special shape spring member with a section extending from one row of links and to a link in the other row, this catch member being actuated so as to disengage the links with a longitudinal sliding motion. The remainder of the watch band sections are of the conventional U-shaped clip and spring type, and consequently it is necessary to employ two different types of sections in the band, with the appearance being slightly different.
It would be desirable to have an adjustable expansion band utilizing the simple and widely accepted U-shaped clip and leaf-spring construction, with provision for disconnecting the sections and reattaching them at desired locations.
Accordingly, one object of the present invention is to provide an improvement in a known type of expansion band which permits engagement or disengagement at selected locations along the band.
Another object of the invention is to provide an economical and improved construction for an adjustable expansion band for a wristwatch.